计算机专业英语教程(第4版)全书译文

1、1We have learned that all computers have similar capabilities and perform essentially the same functions, although some might be faster than others. We have also learned that a computer system has input, output, storage, and processing components; that the processor is the “intelligence” of a comput

2、er system; and that a single computer system may have several processors. We have discussed how data are represented inside a computer system in electronic states called bits. We are now ready to expose the inner workings of the nucleus of the computer system the processor. 我们已经知道，所有的计算机都具有相似的能力，并且在

3、本质上执行相同的功能，尽管一些可能会比另一些快一点。我们也知道，一个计算机系统具有输入，输出，存储和处理部件；处理器是一个计算机系统智能核心，并且一个计算机系统可以有许多个处理器。我们已经讨论过如何在计算机系统内部，用被称作“位”的电子状态来表现数据，现在我们要弄明白计算机系统的核心，即处理器，的内在的工作方式。The internal operation of a computer is interesting, but there really is no mystery to it. The mystery is in the minds of those who listen to h

4、earsay and believe science-fiction writer. The computer is a nonthinking electronic device that has to be plugged into an electrical power source, just like a toaster or a lamp.计算机的内部操作很有意思，但确实没有什么神秘可言。所谓的神秘只是存在于那些听信传闻和相信科幻小说作家的人的意识中。计算机就是一种没有思想的需要接通电源的电子设备而已，与烤面包机和台灯差不多。Literally hundreds of differ

5、ent types of computers are marketed by scores of manufacturers 1. The complexity of each type may vary considerably, but in the end each processor, sometimes called the central processing unit or CPU, has only two fundamental sections: the control unit and the arithmetic and logic unit. Primary stor

6、age also plays an integral part in the internal operation of a processor. These three primary storage, the control unit, and the arithmetic and logic unit work together. Lets look at their functions and the relationships between them.不加夸张地讲，市场上有几百种不同类型的计算机在销售.每种电脑在复杂性上可能有很大区别，但归根结底,每种处理器，有时称为中央处理器即c

7、pu，只有两个基本部分:控制单元和计算逻辑单元.主内存在处理器内部操作中也是一个不可缺少的部分.这三个部件-主内存，控制单元和计算逻辑单元-一起工作.然我们看看它们(各自的)功能和它们之间的联系。 Unlike magnetic secondary storage devices, such as tape and disk, primary storage has no moving parts. With no mechanical movement, data can be accessed from primary storage at electronic speeds, or cl

8、ose to the speed of light. Most of todays computers use DRAM (Dynamic Random-Access Memory) technology for primary storage. A state-of-the-art DRAM chip about one eighth the size of a postage stamp can store about 256,000,000 bits, or over 25,600,000 characters of data!主存与其他的辅助存储器（如：磁带、硬盘）不一样的是，主存不含

9、有运转部件。由于没有机械运转的需要，主存种数据访问可以达到电子的速度，或接近于光速。当今计算机的主存大多数使用DRAM（动态随机存取存储器）技术。目前最新的工艺水平是：一块只有大约1/8张邮票大小的DRAM芯片却可以存储大约256,000,000位，约25,6000,000个字符的数据。Primary storage, or main memory, provides the processor with temporary storage for programs and data. All programs and data must be transferred to primary s

10、torage from an input device (such as a VDT) or from secondary storage (such as a disk) before programs can be executed or data can be processed. Primary storage space is always at a premium; therefore, after a program has been executed, the storage space it occupied is reallocated to another program

11、 awaiting execution.主存储器，也就是说内存，用于为处理器暂时存放程序和数据。所有的程序和数据在被操作之前必须从输入设备（如VDT）或者辅助存储器转存到主存储器中。主存储器存储容量通常是相当有限的，因此，在一个程序执行结束，它所占用的存储空间必须被重新分配给其它正在等待执行操作的程序。Figure 1-1 illustrates how all input/output (I/O) is “read to” or “written from” primary storage. In the figure, an inquiry (input) is made on a VDT

12、. The inquiry, in the form of a message, is routed to primary storage over a channel (such as a coaxial cable). The message is interpreted, and the processor initiates action to retrieve the appropriate program and data from secondary storage 3.The program and data are “loaded”, or moves, to primary

13、 storage from secondary storage. This is a nondestructive read process. That is, the program and data that are read reside in both primary storage (temporarily) and secondary storage (permanently). The data are manipulated according to program instructions, and a report is written from primary stora

14、ge to a printer.图 1-1描述了输入/输出设备与主存储器间的读和写过程。在图中，VDT发出一个输入请求，请求是以消息模式通过通道（如同轴电缆）发送到主存储器。这个查询被解释，处理器发起操作从辅助存储器中调用合适的程序和数据。程序和数据从辅助存储器传送到主存储器中，这是一个非破坏性的读取过程，也就是说，程序和数据同时存在于主存（临时保存）和辅助存储器（永久保存）中。根据程序指令的指示，处理器对数据进行操作，并从主存传送一份报告到打印机。A program instruction or a piece of data is stored in a specific primary

15、storage location called an address. Addresses permit program instructions and data to be located, accessed, and processed. The content of each address is constantly changing as different programs are executed and new data are processed.程序指令和数据是存储在主存中一个特殊的位置，称为地址空间。通过地址空间可以实现计算机对程序指令和数据的定位、访问和处理。地址空间

16、的内容是经常变化的，这是由于计算机一直在执行不同的程序和数据。Another name for primary storage is random-access memory, or RAM. A special type of primary storage, called read-only memory (ROM), cannot be altered by the programmer. The contents of ROM are “hard-wired” (designed into the logic of the memory chip) by the manufacture

17、r and can be “read only”. When you turn on a microcomputer system, a program in ROM automatically readies the computer system for use. Then the ROM program produces the initial display screen prompt.主存储器也称为随机存取存储器，或RAM。还有一种特殊的主存储器，称为只读存储器（ROM），这种存储器不能被程序更改存放的内容。ROM的内容是被生产商通过硬件电路写入的，并且不能被重写。当你启动计算机，R

18、OM中的一个程序会自动就绪等待计算机系统的调用，然后在显示器中显示开机提示。A variation of ROM is programmable read-only memory (PROM). PROM is ROM into which you, the user, can load “read-only” programs and data. Once a program is loaded to PROM, it is seldom, if ever, changed 4. However, if you need to be able to revise the contents o

19、f PROM, there is EPROM, erasable PROM. Before a write operation, all the storage cells must be erased to the same initial state.可编程只读存储器（PROM）是另一种ROM，它可以载入只读的程序和数据，一旦载入，将不再改变。然而，若果你需要去修正PROM的内容，可以使用可擦可编程只读存储器。EPROM在进行一次写操作之前，所有的存储单元必须被还原为同一初始状态。A more attractive form of read-mostly memory is electri

20、cally erasable programmable read-only memory (EEPROM). It can be written into at any time without erasing prior contents; only the byte or bytes addressed are updated.一种更吸引人的可改写只读存储器是电可擦除可编程只读存储器 (EEPROM)。它可以在任何时候写入，而且不会擦除以前的内容；只会更新被寻址的字节。The EEPROM combines the advantage of nonvolatility with the f

21、lexibility of being updatable in place 6, using ordinary bus control, address, and data lines.电可擦可编程存储器把非易失性优点和可更新、需要更新的地方的灵活性结合起来，修改时使用普通的总线控制线、地址线和数据线。Another form of semiconductor memory is flash memory (so named because of the speed). Flash memory is intermediate between EPROM and EEPROM in both

22、 cost and functionality. Like EEPROM, flash memory uses an electrical erasing technology. An entire flash memory can be erased in one or a few seconds, which is much faster than EPROM. In addition, it is possible to erase just blocks of memory rather than an entire chip. However, flash memory does n

23、ot provide byte-level erasure 7. Like EPROM, flash memory uses only one transistor per bit, and so achieves the high density of EPROM.另一种半导体记忆体是闪存（意味着速度快）。闪存在性价比上处于EPROM和EEPROM之间，它使用电擦写技术。整个闪存的内容可以在一到几秒内被清除，这是远快于EPROM的。另外，它还可以对部分记忆块而不是整个存储器进行清除。然而，闪存并不提供字节级的擦除。像EPROM，闪存只使用一个晶体管每比特，因此可以实现高密度的EPROM。Ca

24、che MemoryProgram and data are loaded to RAM from secondary storage because the time required to access a program instruction or piece of data from RAM is significantly less than from secondary storage. Thousands of instructions or pieces of data can be accessed from RAM in the time it would take to

25、 access a single piece of data from disk storage 8. RAM is essentially a high-speed holding area for data and programs. In fact, nothing really happens in a computer system until the program instructions and data are moved to the processor. This transfer of instructions and data to the processor can

26、 be time-consuming, even at microsecond speeds. To facilitate an even faster transfer of instructions and data to the processor, most computers are designed with cache memory. Cache memory is employed by computer designers to increase the computer system throughput (the rate at which work is perform

27、ed).程序和数据从辅助存储器装载到RAM中是因为对RAM中的程序指令和数据的访问时间要明显的少于从辅助存储器访问。数以千条的指令和数据能被访问而只需花费从硬盘访问一次数据的时间。RAM是数据和程序的重要的高速存放区，事实上，计算机系统不会进行任何操作直到程序指令被传入处理器进行执行，这种指令和数据的传输是需要花费时间的，即使传输速度已经是以纳秒来计算了。为了能更快速的传输指令和数据，大多数计算机设计使用高速缓存。计算机设计者使用高速缓存来提高计算机系统的总处理能力（工作效率）。Like RAM, cache is a high-speed holding area for program i

28、nstructions and data. However, cache memory uses SRAM (Static RAM) technology that is about 10 times faster than RAM and about 100 times more expensive. With only a fraction of the capacity of RAM, cache memory holds only those instructions and data that are likely to be needed next by the processor

29、. Two types of cache memory appear widely in computers. The first is referred to as internal cache and is built into the CPU chip. The second, external cache, is located on chips placed close to the CPU chip. A computer can have several different levels of cache memory. Level 1 cache is virtually al

30、ways built into the chip. Level 2 cache used to be external cache but is now typically also built into the CPU like level 1 cache.和RAM一样，高速缓存也是程序指令和数据的高速存储区。然而，高速缓存使用静态RAM技术，这种技术比RAM在速度上要高出10倍，价格上高出100倍。cache只保存内存中那一小部分最有可能被处理器执行的指令和数据。两种类型的cache广泛应用于计算机，第一种被植入cpu中的叫做内部高速存储，第二种是外部高速存储，它位于那些靠近cpu的芯片中

31、。一台计算机可以拥有几个不同级别的高速缓存。一级缓存实际上总是植入芯片中，二级缓存过去常常作为外部高速缓存，但是现在也像一级缓存植入cpu内部。2.1Optical laser disk technology eventually may make magnetic-disk and magnetic tape storage obsolete. With this technology, the read/write head used in magnetic storage is replaced by two lasers. One laser beam writes to the re

32、cording surface by scoring microscopic pits in the disk, and another laser reads the data from the light-sensitive recording surface. A light beam is easily deflected to the desired place on the optical disk, so an access arm is not needed.光盘技术最终可能使磁盘和磁带存储淘汰。用这种技术，磁存储器所用的读/写头被两束激光代替。一束激光通过在光盘上刻制微小的凹

33、点，对记录表面进行写；而另一束激光用来从光敏感的记录表面读取数据。由于光束容易被偏转到光盘上所需要的位置，所以不需要存取臂。Optical laser disks are becoming a very inviting option for users. They are less sensitive to environmental fluctuations, and they provide more direct-access storage at a cost that is much less per megabyte of storage than the magnetic-di

34、sk alternative. Optical laser disk technology is still emerging and has yet to stabilize; however, at present there are three main categories of optical laser disks. They are CD-ROM, recordable CD-R and rewritable CD-RW, and magneto-optical disk.对用户而言，光盘正成为最有吸引力的选择。它们(光盘)对环境变化不太敏感，并且它们以每兆字节比磁盘低得多的存储

35、器价格提供更多的直接存取存储器。光盘技术仍在出现，并且还需要稳定；然而，目前有三种主要类型的光盘。它们是CD-ROM、WORM盘和磁光盘。CD-ROMIntroduced in 1980, the extraordinarily successful CD, or compact disk, is an optical laser disk designed to enhance the recorded reproduction of music. To make a CD recording, the analog sounds of music are translated into t

36、heir digital equivalents and stored on a 4.72-inch optical laser disk. Seventy-four minutes of music can be recorded on each disk in digital format by 2 billion digital bits. With its tremendous storage capacity, computer-industry entrepreneurs immediately recognized the potential of optical laser d

37、isk technology. In effect, anything that can be digitized can be stored on optical laser disk: data, text, voice, still pictures, music, graphics, and video.1980年引入的，非常成功的CD，或紧密盘是设计来提高音乐的录音重放质量的光盘。为了制作一张CD，把音乐的模拟声音转换成等价的数字声音，并且存储在一张4.72英寸的光盘上。在每张光盘上可以用数字格式（用20亿数字位）记录74分钟的音乐。因为它的巨大存储容量，计算机工业的企业家们立刻认识

38、到光盘技术的潜力。事实上，任何可以被数字化的东西都能存储在光盘上：数据、正文、声音、静止图象、音乐、图形和视频。CD-ROM(pronounced cee-dee-ROM) is a spinoff of audio CD technology. CD-ROM stand for compact disk-read only memory. The name implies its application. CD-ROM disks, like long-playing record albums, are “pressed” at the factory and distributed wi

39、th their prerecorded contents(for example, the complete works of Shakespeare or the first 30 minutes of Gone with the wind). Once inserted into the disk drive, the text, video images, and so on can be read into primary storage for processing or display; however, the data on the disk are fixedthey ca

40、nnot be altered. This is in contrast, of course, to the read/write capability of magnetic disks.CD-ROM（读作CDROM）是音频CD技术的副产品。CD-ROM代表紧密盘只读存储器。该名字隐含了它的应用。只读光盘与 (能长期播放的) 唱片一样，在工厂里“压制”并带着预先录好的内容 (如莎士比亚全集，或电影“飘”的前30分钟部分)，分发出去。一旦光盘插入光盘驱动器，正文、视频图像等等就能读入主存进行处理或显示；然而，在只读光盘上的数据是固定的它们不能被改变。当然，这是与磁盘的读/写能力不同的。The

41、 tremendous amount of low-cost dir-access storage made possible by optical laser disks has opened the door to many new applications.大量的、低成本直接存取存储器（是光盘使之成为可能）已经打开了通向许多新应用的大门。CD-R AND CD-RWCD-R and CD-RW both allow user to store data on compact discs, but only data on rewriteable CDs can be erased and

42、 overwritten. CD-R discs can only be written to once. Both types of discs look very similar to CD-ROM discs. Recordable CDs are commonly used to store music files, allowing home users to make high-quality personalized music CDs. CD-RW discs can be written to and erased similar to floppy disk. Conseq

43、uently, they are a good alternative for large file storage, as well as for creating a “master” disc before burning a CD-R discs(most CD-RW drives can write to both CD-RW and CD- R discs, but some CD and CD-R drives cannot read CD-RW discs). CD-R and CD-RW drives also read CD-ROM discs. However, CDs

44、will be eclipsed BY DVDs, once that technology becomes improved and standardized.CD-R和CD-RW都允许用户存储数据在光盘上，但是只有那些在可复写cd中的数据能被擦除和重写。Cd-r光盘只能被写入一次。这俩种光盘看起来与只读cd光盘差不多。可记录cd管片通常用于存储音乐文件，这样可以允许家庭用户制作高质量的个人音乐唱片。Cd-rw光盘就像软盘那样能被重写和擦除。因此，他们是大容量文件存储的另一种不错选择，同时也作为主盘在对cd-r光盘进行刻入之前（大多数的可擦写光盘驱动器可以读取cd-rw和cd-r光盘，但是也

45、有一些cd驱动器和cd-r驱动器不能读cd-rw光盘）。Cd-r和cd-rw驱动器也可以读cd-rom光盘，然而，cd将会被dvd所替代，一旦dvd的技术完全成熟和标准化。Magneto-Optical DiskMagneto-Optical disk offers promise that Optical laser disks will become commercially viable as a read-and-write storage technology. The 5and1/4inch disks can store up to 1,000Mb. At present, ma

46、gneto-optical disks are too expensive and do not offer anywhere near the kind of reliability that users have come to expect of magnetic media. In addition, the access times are relatively slow, about the same as a low-end Winchester disk.磁光盘有希望使得激光盘成为商业上可行的读/写存储技术。5*1/4英寸的磁光盘可以存储高达1000Mb。目前磁光盘太贵且根本未

47、达到用户对磁介质所期望的那种可靠性。此外，存取时间相对而言比较慢，大约与低档温彻斯特盘相同。As optical laser disk technology matures to reliable, cost-effective, read/write operation, it eventually may dominate secondary storage in the future as magnetic disks and type do today.随着光盘技术成熟到可靠，性能价格合算，可读/可写，将来它最终会象现在磁盘、磁带那样统治二级存储器。DVDsThe acronym DV

48、D(for digital versatile disc, or digital video disc) refer to a relatively new high-capacity optical storage format that can hold from 4.7GB to 17GB, depending on the number of recording layers and discs sides being used. A standard single layered, single-sided DVD can store 4.7GB of data; a two-lay

49、ered standard enhances the single-side layer to 8.5GB. DVD can be double-sided with a maximum storage of 17GB per disc. The DVD was initially developed to store the full contents of a standard two-hour movie, but is now also used to store computer data and software. DVD-ROM technology is seen by man

50、y as the successor to music CDs, computer CD-ROMs, and prerecorded VHS videotape that people buy and rent for home viewing-in other words, read-only products. DVD-R is DVD rewritable(similar to CD-W). The user can write to the disk only once. DVD-RW is DVD recordable(similar to CD-RW). The user can

51、erase and rewrite to the disk multiple times. Only one-sided disks can be used for both DVD-R and dvd-rw. Most DVD drives can play both computer and audio CDs, but you cant play DVDs in a CD drive.这个缩写影碟（数字化视频光盘或数字视频光盘），指的是相对较新的高容量光存储格式取决于光盘记录层和边数，可以从4.7 GB的持有以17 GB，被使用。一个标准的单层单面的DVD可以存储4.7 GB的数据，一两

52、个层次的标准，增强了单面层到8.5 GB的。 DVD可双面的每件17 GB的最大存储。该DVD最初是存储标准的全部内容的两个小时的电影，但现在还用于存储计算机数据和软件。DVD - ROM技术是被许多人视为对音乐CD，电脑光盘和人们购买和租赁的预先录制的家庭录影带的后续，换句话说，只读的产品。DVD-R是可记录的DVD（就像CD-R那样）。用户可以对其进行一次写入。DVD-RW是可擦写的（类似的CD - RW），用户可擦除和重写磁盘多次。DVD-R和DVD-RW都是单面光盘。所有的DVD驱动器可以同时播放电脑和音频CD。但是，不能在CD播放机上应用DVD光盘。 DVD Forum Receiv

53、es Top Information Technology Industry Award for Creation of Unified Specification for Next Multimedia EraDVD论坛因建立下一代数字多媒体的统一规范而获得最高信息技术工业奖The DVD Forum today announced that it has received the 1997 PC Magazine Award for Technical Excellence in the category of “Standards”, in recognition of the Foru

54、ms successful development of the dvd-rom specification.DVD论坛今天宣布，因该论坛成功制定了DVD-ROM规范而获得1997年PC杂志的 (制定标准的) 卓越技术奖。“New standards are particularly important, since they promise to bring higher levels of technology innovation and market compatibility to todays technology users,” said by Michael J. Miller

55、, editor-in-chief of PC Magazine.” DVD-ROM is a compelling technology that was chosen because its a familiar format that brings a wealth of new computing, educational, gaming and entertainment possibilities to the user.”“新的标准特别重要，因为它们承诺把更高级的技术革新和市场兼容性带给今天的技术用户，”PC杂志主编Michael J. Miller说，“DVD-ROM是被选出的

56、激发兴趣的技术，因为它是一种熟悉的格式，它把大量的新计算、新教育、新游戏和新娱乐的可能性带给用户。”In the Award citation to DVD-ROM technology, PC Magazine referred to DVD as the format that will ”replace the CD-ROM as the primary means of PC content distribution. ”Representatives of three companies involved in development of the specification, Hi

57、tachi Ltd. , Matsushita Electric Industrial Company(Panasonic) and Toshiba Corporation, accepted the award on behalf of the DVD Forum in a ceremony held on November 17 at COMDEX 97 in Las Vegas.在对DVD-ROM技术的颁奖词中, PC杂志称，DVD将会“代替CD-ROM作为PC内容 (即各种软件和资料) 传播的主要手段。”参加规范开发的三个公司的代表（日立，松下，东芝）以DVD论坛的名义在11月7日，L

58、as Vegas COMDEX 97 举行的庆祝典礼上接受该项奖。“Products based on specifications defined by the DVD Forum are now shipping in volume to the worldwide computer and consumer electronics markets, and the Award for Technical Excellence adds to the markets validation of the success of the standards process, ”said Koji

59、 Hase, General Manager of the DVD Products Division at Toshiba Corporation and a founding member of the DVD Forum. ”We are extremely pleased to see the work of the DVD Forum recognized as one of the key technical achievements in the personal computer industry, particularly as the Forum expands the scope of it